Means for indicating flaws in materials



June 27, 1939. 5, SQKQLQFF 2,164,125

MEANS FOR INDICATING FLAWS IN MATERIALS Filed Aug, 21, 1937 2 Sheets-Sheet l June 27, 1939. s, SOKOLOFF 2,164,125

MEANS FOR INDICATING FLAWS IN MATERIALS Filed Aug. 21, 1937 2 Sheets-Sheet 2 a v W4; Ti: 1 (b oscilafor fire/22% afi afafi I/ '1 7 1v MEANS FOR INDICATING FLAWS IN MATERIALS Sergey Sokoloij, Leningrad, Union of Soviet Socialist Republics Application August 21,

1937, Serial No. 160,344

In Union of Soviet Socialist Republics June 8,

3 Claims.

This invention relates to means for determining and depicting the nature of flaws within materials.

In order to detect flaws within solid materials, it has been proposed to examinethe material by means of X-rays or to form a magnetic field in and around the article under observation and to analyze the induction of the magnetic field in order to determine the extent and character of the fiaw by observing the distortion of the magnetic lines of force. It has not been possible by any of the previous methods toobtain a visible image of the faulty places within the body under test.

An object of the present invention is to obtain a true image of a flaw even though the fault is located in the interior of the body.

Other and further features and objects of the invention will be more apparent to those skilled in the art upon a consideration of the appended drawings and the following description wherein two constructional forms of apparatus for carrying out the invention are disclosed.

In the drawings:

Figure 1 diagrammatically illustrates apparatus having spiral disks for reproducing the image of a flaw.

Figure 2 is a plan view of one of the disks shown in Figure 1.

Figure 3 is a plan view of the other disk.

Figure 4 is a diagrammatic view illustrating a modification of the apparatus shown in Figure 1.

Referring to the drawings the body to be examined such as a thick steel block I has a flaw in the form of a gap 20. A piezo quartz plate 3 provided with only one coating is arranged against the body I. The second coating is formed by the steel block I itself. If the quartz plate 3 is excited by high frequency oscillations by means of a generator 4, the plate 3 is oscillated and transmits a beam of ultra-acoustic rays 2 perpendicularly to its surface through the block I. In other words, elastic oscillations are produced in the block I which spread in the direction of the rays. The rays 2 pass freely to the opposite side of the block except the parts located opposite the gap where the elastic oscillations are interrupted.

A second piezo quartz plate 5 is arranged at the point where the rays 2 pass out of the body I and the plate 5 is formed to have the same natural frequency as the plate 3. In the immediate vicinity of the rear side of the quartz plate 5 a rotary disk 6 of insulating material such as ebonite is arranged. The disk 6 is provided with a plurality of radially extending conductors 2| which are terminated at I so that the ends of the conductors form a spiral outline as illustrated in Fig. 2. Each conductor 2| is electrically connected to a sleeve or slip ring 22 secured to the 5 shaft 8. A brush 23 connected to the circuit of the amplifier 9 is arranged to engage the slip ring 22.

A scanning of the surface of the quartz plate 5 takes place during the rotation of the disk 6. In other words, the surface ofthe quartz plate is traversed by an end I of each conductor 2| so that the ends of the conductors scan the plates.

The ultra-acoustic rays 2 passing from the quartz plate 3 through the body I to the quartz plate 5 produce resonance oscillations in the latter since only those points of the plate 5 oscillate which are not covered by the flaw 20, in the body I.

The conductor ends I serve as the second coating of the plate 5 and each takes off the electric charge produced on the plate 5. 'In this manner an electric image is produced in the form of a distribution of the electric charges on the quartz plate 5 and the electric image is lead therefrom by the conductors 2I.

The electric impulses thus produced are in. tensified in the amplifier 9 and supplied to a neon lamp III which is arranged behind a second disk I I also secured to the shaft 8. Apertures 24 are arranged in the disk I I and distributed identically with the arrangement of the conductor ends 1 or according to a spiral which reproduces the scanning in lines on a screen I2 of ground glass. Consequently, a. picture is formed on the screen I2 according to the modulation of the neon lamp Ill so as to reproduce the distribution of the electric charges of the quartz plate 5 and consequently produce a shadow image of the flaw 20 in the body I.

In the constructional form illustrated in Fig. 4, a cathode ray tube is used for scanning the electric image and for converting the same into a picture. The quartz plate 5, which is excited by the ultra-acoustic rays 2' passing through the body I, lies closely against the end of a cathode ray tube I3 which is designed as a television transmitter. The inner side of the end of the tube I3 is provided with a network of very small metal ,electrqdes li separate or insulated from one 5 another. This network of electrodes serves as the second coating of the quartz plate 5 on which are produced electric charges corresponding to oscillations excited by the ultra-acoustic rays 2 which pass to the quartz plate 5 after penetrating the body I. The electrode points I4 lying opposite the flaw do not receive any charges.

In the tube l3, a cathode ray I5 is moved in two directions perpendicular to each other and therefore performs a line scanning. This cathode ray takes off from the electrodes Hi the corresponding electric charges and after amplification the electric impulses are transmitted to the sleeve 26 of the second cathode ray tube IE or the receiver tube. The oscillating cathode ray I! produces on the screen la a visible image of the faulty place of the body I.

It has been found that the electrode network I! in the tube H can be eliminated since the electron ray I 5 can also take off the electric charges produced on the quartz plate 5.

Thus a .distribution of electrical charges is produced on a limited surface area of the quartz plate 5 which corresponds to the outline of the flaw within the interior of the body I. The electrical image thus produced is converted into a visible image by means of television apparatus which may take the form of the scanning disks shown in Fig. 1 or the cathode ray tubes illustrated in Fig. 4. The present invention therefore provides an arrangement for producing electrical charges which represent an invisible image of the shadow produced by the outline of the flaw and the invisible image is converted into a picture which clearly indicates the extent and character of the flaw within the material under examination.

Although the preferred embodiments of the apparatus for carrying out the invention have been disclosed it will be appreciated that modifications may be made therein by those skilled in the art. Such modifications may be made without departing from the spirit and scope of the invention as set forth in the appended claims.

I claim:

1. Apparatus for detecting flaws in articles and for producing a visible image thereof comprising in combination, a high-frequency generator, a piezo-quartz plate which produces ultra-acoustic oscillations under the action of said high frequency, means for applying the high frequency current to said plate arranged against one side of the article to be examined, a second quartz plate adjusted to the same frequency as that of the first quartz plate arranged against the opposite side of the article to be examined for receiving the oscillations passing through the article, a television transmitter for taking off the electric charges from the surface of the second quartz plate, a television receiver for converting the electric impulses from the transmitter into a visible image corresponding to the spatial distribution of the electric charges on the second quartz plate.

2. Apparatus for detecting flaws in articles and for producing a visible image thereof comprising in combination, a high-frequency generator, a quartz plate for generating ultraacoustic oscillations under action of the generator current arranged against one side of the article to be examined, means for applying the high frequency current to said plate, a second quartz plate arranged against the opposite side of the article and receiving the oscillations passing through the article, an electron ray tube arranged with an end thereof adjacent the second quartz plate, a second electron ray tube serving as a receiver and having a screen upon which the visible image of the outline of the flaw appears, which image corresponds to the spatial distribution of the electric charges on the second quartz plate.

3. Apparatus for detecting flaws in articles and for producing a visible image thereof comprising in combination, a high frequency generator, a piezo-quartz plate for generating ultraacoustic oscillations under action of the generator current, said plate being arranged against the article to be examined, means for applying the high frequency current to said plate, a second quartz plate arranged against the opposite side of the article and receiving the ultra-acoustic oscillations passing through the article, a disk of insulating material and means rotating the disk in a plane close to the outer surface of the second quartz plate, conductors secured to said disk and having ends distributed in a spiral line which lies adjacent the second quartz plate, all of said conductors being connected by a sliding contact to an amplifier circuit, a light source modulated by the amplified electric impulses, and a receiver in the form of a second disk mounted to rotate with the first disk and having apertures distributed along a spiral line similarly to the conductor ends of the first disk for producing a visible image of the outline of the flaw corresponding to the spatial distribution of the electric charges on the second quartz plate.

SERGEY SOKOLOFF'. 

